The invention relates to a mini-bicycle
For example, the IKO-Corratec 2001 brochure discloses bicycles with the most varied frames and configurations. The different types of bicycles and bicycle frames offer different advantages, depending on the respective specific primary application.
A generic bicycle is known for example from DE 43 16 366 A1. This bicycle is characterized by a multi-part frame which can be telescoped in and out. In the position of use the telescoping frame is extended in order to have enough space between the seat tube support and the handlebar support. By sliding the telescoping frame parts into one another the bicycle can be folded, requiring less stowage space. Furthermore, the head tube rod is made in two parts and can be swivelled back above the steering tube. In the operating position it can be fixed by a fixing means in which the head tube rod is aligned in a direct axial extension to the steering tube. To enable space-saving folding, the seat tube support together with an additional support means which runs obliquely to the rear can for example be pulled out of the main tube or if necessary inserted again. Basically it will be possible to connect the seat tube to the support tube on the frame part with a swivelling capacity, without this being shown or described in greater detail.
A bicycle which is conventional in terms of its size is also known from U.S. Pat. No. 3,979,136 A. This bicycle also has a two-part main tube, the plane of separation between the two main tubes being located shortly in front of the support point of the seat tube brace. The front main tube section can be swivelled around a vertical swivelling axis until it comes to rest parallel to the rear main tube section in the folded-together position. The seat tube support can swivel around a swivelling axis which lies underneath relative to the rear main tube section. The support braces which run obliquely to the rear from the seat tube brace structure can likewise be folded together in a V-shape so that in the folded-together position the seat tube structure comes to rest essentially parallel to the main tube and in doing so the rear wheel projects through the double brace-shaped seat tube structure. The seat is then behind the rear wheel. The front wheel with the steering tube and the head tube can be swivelled jointly to the rear via a horizontal swivel axis which lies forward on the main tube. The head tube is also supported relative to the main tube via a tiltable support tube structure.
A bicycle structure which is made with a multi-part main tube with a front wheel and two rear wheel axles is fundamentally also known from U.S. Pat. No. 4,824,130 A.
Finally, German utility model DE 81 24 880 U1 discloses a folding motor scooter with optionally a gasoline engine or electric motor.
The object of this invention is to devise, proceeding from the initially mentioned generic prior art, an improved folding bicycle which is especially suitable for towns and cities and can be carried along comparatively easily in the folded state.
The bicycle as claimed in the invention is designed not only to be small, but also be to folded together to be small. It can be easily packed in a motor vehicle or even carried; the wheels are smaller than 12 inches. They can even easily have a size of 7 inches. Therefore the bicycle as claimed in the invention is comparable to so-called roller scooters, therefore known miniscooters which are likewise used to travel quickly in urban areas and can be carried into stores, schools, businesses, government offices, etc.
The bicycle as claimed in the invention is characterized by a main tube which is located comparatively low. In contrast to the generic prior art this main tube is made however, not in two parts or even telescoping, but only in one part. In this way it can be built structurally simply and mainly lighter. There is no conventional bicycle frame.
Furthermore, in the bicycle the upper part of the two-part lead tube (specifically above the separation which joins the two torque tube sections or the tilt axis) is tilted relative to the alignment position of the lower head tube section or steering tube in the forward direction. This makes it possible for enough space to remain for a bicycle rider between the seat and seat tube support and the upper head tube and the handlebar in an overall short design and structural length of the main tube or main tube arrangement.
To be able to easily adjust the bicycle between the unfolded position of use and the folded-up carrying position, the rear assembly brace construction is made such that it is hinged forward on the main tube and trailing on the main tube structure and preferably in the middle area has one axle or articulated axle in order to be able to adjust the rear assembly construction from the position which runs preferably straight in the position of use into the position folded-together in a V shape, in which then the seat tube support is likewise swivelled in the direction of the main tube. In this way completely reliable set-up and folding can be accomplished.
The two-part lead tube preferably has a horizontal tilt axis which is preferably located immediately above the steering tube which ends low. At this point there is also a fixing or clamping means in order to fix the two lead tube sections in the position of use in a fixed relative position to one another.
The rear assembly braces are preferably located in the middle with a hinge so that the head tube and the seat tube can be completely folded away downward in the direction of the low main tube which passes preferably from the steering tube to the dropout. The wheels can be designed to be extremely small, comparable to the initially mentioned miniscooters.
Although the head and seat tube can preferably be folded completely away, it can also be attached removably at least indirectly to the main tube.
Furthermore, it has proven to be favorable for the inner bearing without the inner bearing housing to be screwed directed to the main or frame tube. Since the steering tube is preferably low, similarly to in miniscooters, there is an overly long steering linkage as claimed in the invention. The cranks are made preferably shorter than in a normal bicycle.
For the drive sprocket preferably fewer teeth than in a normal wheel are used. In conventional wheels the chain wheel has at least 11 teeth. In the mini-bicycle as claimed in the invention the number of teeth can be chosen to be much less than 11, so that a chain wheel not only with 10, but even only with 9, 8 or 7 teeth can be easily built.
The mini-bicycle as claimed in the invention preferably does not have gear shifting. It can be provided with a free-wheeling rear wheel or even with a rigid drive so that it can also be ridden backwards. In addition, the mini-bicycle can also be provided with a foot rest in order to be able to place the feet in coasting, especially with a rigid drive. In addition, the foot rests could also project laterally mounted on the rear wheel in order to use the bicycle also as a scooter.
In one alternative and preferably cumulative embodiment, an especially compact bicycle with small dimensions can also be formed by the front part of the main tube between the bottom bracket bearing and the head tube being less than 70% of the rear main tube section between the bottom bracket bearing and the dropout. Preferably the front part of the main section has only half the length of the rear main tube section. The head tube section can be aligned running forward relative to the lower steering tube as compensation.